1. Field of the Invention
Aspects of the present invention relate to an organic thin film transistor and a flat panel display device having the organic thin film transistor, and more particularly, to an organic thin film transistor that can shift a threshold voltage to a desired direction, and a flat panel display device having the organic thin film transistor.
2. Description of the Related Art
Thin film transistors (TFTs) used for flat panel display devices such as a liquid crystal display devices, organic light emitting display devices, or inorganic light emitting display device are used as switching devices that control the operation of each pixel and driving devices that drive the pixel.
TFTs have a semiconductor layer having source and drain regions doped with a high concentration of dopant and a channel region between the source and drain regions, a gate electrode insulated from the semiconductor layer and located on a region corresponding to the channel region, and source and drain electrodes respectively connected to the source and drain regions.
The source and drain electrodes are usually formed of a material having a low work function so as to have smooth current flow. However, due to high contact resistance between the metal and the semiconductor layer, device characteristics are reduced, thereby increasing power consumption.
Organic thin film transistors are advantageous because an organic semiconductor layer can be processed at low temperatures, which means that a plastic substrate can be used. Because of the cost advantages of using a plastic substrate, much active research relating to organic thin film transistors has been recently carried out.
However, there are problems relating to controlling threshold voltage and leakage current in organic thin film transistors.